1. Technical Field
The present disclosure relates generally to a surgical stapling device for applying surgical staples to body tissue. More particularly, the present disclosure relates to a surgical stapling device suitable for performing circular anastomosis and/or treatment to internal walls of hollow tissue organs.
2. Background of Related Art
Anastomosis is the surgical joining of separate hollow organ sections. Typically, an anastomosis procedure follows surgery in which a diseased or defective section of hollow tissue is removed and the remaining end sections are to be joined. Depending on the desired anastomosis procedure, the end sections may be joined by either circular, end-to-end or side-to-side organ reconstruction methods.
In a circular anastomosis procedure, the two ends of the organ sections are joined by means of a stapling instrument which drives a circular array of staples through the end section of each organ section and simultaneously cores any tissue interior of the driven circular array of staples to free the tubular passage. Examples of instruments for performing circular anastomosis of hollow organs are described in U.S. Pat. Nos. 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745, 4,576,167, and 4,473,077, each of which is incorporated herein in its entirety by reference. Typically, these instruments include an elongated shaft having a handle portion at a proximal end to actuate the instrument and a staple holding component disposed at a distal end. An anvil assembly including an anvil rod with attached anvil head is mounted to the distal end of the instrument adjacent the staple holding component. Opposed end portions of tissue of the hollow organ(s) to be stapled are clamped between the anvil head and the staple holding component. The clamped tissue is stapled by driving one or more staples from the staple holding component so that the ends of the staples pass through the tissue and are deformed by the anvil head. An annular knife is concurrently advanced to core tissue with the hollow organ to free a tubular passage within the organ.
Besides anastomosis of hollow organs, surgical stapling devices for performing circular anastomosis have been used to treat internal hemorrhoids in the rectum. Hemorrhoids are masses of tissue in the anus containing enlarged blood vessels. Internal hemorrhoids are inside the anal canal; external hemorrhoids lie outside the anal canal. In hemorrhoidectomy, the hemorrhoids are removed. Stapled hemorrhoidopexy is a surgical procedure in which the stapling device is used to remove tissue just above the hemorrhoids in order to pull the hemorrhoids back up inside the rectum and reduce the symptoms. The staples interrupt the blood flow of the superior hemorrhoidal arterial branches, cutting off the blood supply, thus causing the hemorrhoids to shrink.
During the use of a circular stapling device for hemorrhoid treatment, the anvil head and the staple holding component of the device are inserted through and into the rectum with the anvil head and the stapling holding component in an open or unapproximated position. Thereafter, a purse string suture is used to pull the internal hemorrhoidal tissue and/or mucosal tissue toward the anvil rod. Next, the anvil head and the staple holding component are approximated to clamp the hemorrhoidal tissue and/or mucosal tissue between the anvil head and the staple holding component. The stapling device is fired to remove the hemorrhoidal tissue and/or mucosal tissue and staple the cut.
Typically, such surgical stapling devices include a movable handle or trigger which is movable through a firing stroke to simultaneously affect formation of a circular array of staples and coring or cutting of tissue. When the movable handle is moved through only a portion of the firing stroke during firing of the stapling device, the circular array of staples may not be adequately formed, nor may the tissue be adequately cut. In current instruments, when the movable handle is released after firing of the stapling device, the movable handle is returned by a biasing member to its pre-fired position. This occurs whether or not the handle has been moved through a complete firing stroke or only a portion of the firing stroke. Thus, where a surgeon inadvertently fails to move the handle or trigger to complete the firing stroke and acceptable staple formation and cutting are not affected, the handle will still return to its pre-fired position.
Accordingly, it would be desirable for a surgical stapling device to include a mechanism for substantially preventing the movable handle from prematurely returning to its pre-fired position until the movable handle has been moved substantially through the full firing stroke.